Various telecommunications and broadcast communication companies have installed thousands of miles of fiber optic cable. In order for the complete communication system to function properly, the cables belonging to the different companies are necessarily spliced together at locations where the communication signals are passed from own company's responsibility to another. As these fiber cables are damaged by acts of God, such as lightning, or by contractors as they excavate around the cable, it is necessary to locate the precise area of the damaged cable. Various techniques known in the art, for example, Optical Time Domain Reflectivity (OTDR), may be used to determine the precise geographic location of the fault. An optical time domain reflectometer is an optoelectronic instrument that characterizes an optical fiber by injecting a series of optical pulses into the fiber under test, extracting light that is backscattered and reflected back, measuring and integrating the intensity of the return pulses as a function of time, and plotting the integration as a function of fiber length. From this plot, the fiber's length, overall attenuation (including splice and connector losses), as well as the location of any faults or breaks can be estimated.
Backscattered light, commonly referred to as Rayleigh scattering, is typically weak, and is due to refractive index fluctuations and inhomogeneities in the fiber core. The strength of the backscattered signal is primarily dependent upon the peak power and width of the test pulse. The backscattered signal may be used to detect faults such as micro-bends or splice losses, as well as to measure overall attenuation.
Reflective signals, commonly referred to as Fresnel reflections, are somewhat stronger and are caused by discontinuities in the fiber. The strength of the reflected signal is primarily dependent upon the peak power of the test pulse. Reflective signals may be used to determine the overall length of the fiber line, and to detect breaks in the fiber reflective connectors and splices of fiber having different indices of refraction.
While conventional OTDRs have proven extremely useful in determining the physical location of a fiber fault, there is no way to determine, from that measurement, the “owner” of the cable at the fault location. As more and more communication networks control different geographic areas of an interconnected fiber network, it will become increasingly difficult to assign the various cables with the various network providers.
Thus, a need remains in the art for an arrangement that is capable of defining both the location of a fiber optic cable fault as well as the “owner” of the fiber at the location of the fault.